1. Field of the Invention
The present invention relates to color processing for correcting differences in color appearance.
2. Description of the Related Art
In order to match color representations between different media, e.g., a color displayed on a monitor and a color on a printout, various color conversion methods have been proposed. For example, in order to achieve matching of color presentations between different media, there has been proposed a method of correcting correction factors such that the XYZ value of one medium corresponds with that of the other medium.
However, color appearances on different media do not always match even when their XYZ values correspond to each other. The color matching functions defined by Commission Internationale de l'Eclairage (CIE) are based on the average values of a plurality of subjects (in other words, the vision sensitivity or chromatic vision characteristics of a standard observer), and color matching functions differ among individuals. Therefore, when an image is actually observed, its color appearances on different media do not always match.
Color matching functions are expressed as a function of light wavelength. Therefore, in order to correct the differences in color matching functions on an image with a high accuracy, it is desirable to correct the measurement data (to be referred to as spectral data or spectral image data, hereinafter) of the spectral radiance.
In addition, a technique of absorbing differences in color appearance due to differences in the human chromatic vision characteristics is also disclosed. This technique performs luminance correction on an HSV color space and color correction on an RGB color space such that the color appearance observed by one person who has chromatic vision characteristics with difficulty in distinguishing red from green becomes close to the color appearance observed by another person who has standard chromatic vision characteristics.